Sodium tetrapropylborate
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| Names | |
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| IUPAC name
Sodium tetrapropylboranuide
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| Other names
Sodium tetrapropylborate
Sodium tetra-n-propylborate | |
| Identifiers | |
3D model (JSmol)
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| ChemSpider | |
| EC Number |
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| MeSH | C489231 |
PubChem CID
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| Properties | |
| (C3H7)4BNa | |
| Molar mass | 206.16 g·mol−1 |
| Related compounds | |
Other anions
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Sodium tetraphenylborate |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Sodium tetrapropylborate is an ionic organoboron compound used as a derivatization reagent for chromatography of organometallic pollutants. It is a white hygroscopic powder.[1] It is stable in aqueous solution, but pyrophoric in air; it can be stored as a solution in tetrahydrofuran for multiple weeks.[2]
Synthesis
[edit]Synthesis begins with the propylation of boron trifluoride diethyl etherate with propylmagnesium bromide, yielding tripropylborane[1]:
- BF3·(C2H5)2O + 3 C3H7MgBr → B(C3H7)3 + 3 MgBrF + (C2H5)2O
Tripropylborane can then react with propylsodium or with 1-chloropropane and sodium metal to yield the tetrapropylborate.[3]
Applications
[edit]The tetrapropylboranuide anion is a reagent for the propylation of organometallic compounds, including organotin, organomercury, and organolead compounds of interest to environmental and public health research.[according to whom?] As environmental organometallic contaminants often occur as ions, peralkylation is needed to render them volatile for gas chromatography. This reaction can be performed with Grignard reagents such as propylmagnesium bromide, but their reactivity with water greatly complicates the process for environmental samples.
For any organyl(s) R, the reactions of interest for derivatization proceed as follows:[4]
- R4−n(Sn,Pb)n+ + n NaB(C3H7)4 ⇌ R4−n(Sn,Pb)(C3H7)n + n B(C3H7)3 + n Na+
- RHg+ + NaB(C3H7)4 ⇌ RHgC3H7 + B(C3H7)3 + Na+
As many organometallic pollutants contain methyl, ethyl, or butyl groups, alkylation with any of these groups would render the pollutants indistinguishable from inorganic material present in the sample: triethyl lead is 100 times as toxic as inorganic lead,[5] but after perethylation, both would yield tetraethyllead.
By introducing propyl groups, less common in pollutants of interest, sodium tetrapropylborate allows the analysis of methyl, ethyl, and butyl compounds in a single process.[1][2]
References
[edit]- ^ a b De Smaele, Tom; Moens, Luc; Dams, Richard; Sandra, Pat; Van Der Eycken, Johan; Vandyck, Jos (1998). "Sodium tetra(n-propyl)borate: A novel aqueous in situ derivatization reagent for the simultaneous determination of organomercury, -lead and -tin compounds with capillary gas chromatography–inductively coupled plasma mass spectrometry". Journal of Chromatography A. 793: 99–106. doi:10.1016/S0021-9673(97)00886-8.
- ^ a b Schubert, P.; Rosenberg, E.; Grasserbauer, M. (2000). "Comparison of sodium tetraethylborate and sodium tetra(n-propyl)borate as derivatization reagent for the speciation of organotin and organolead compounds in water samples". Fresenius' Journal of Analytical Chemistry. 366 (4): 356–360. doi:10.1007/s002160050072. PMID 11220318.
- ^ Honeycutt, Julian B.; Riddle, James M. (1961). "Preparation and Reactions of Sodium Tetraethylboron and Related Compounds1". Journal of the American Chemical Society. 83 (2): 369–373. doi:10.1021/ja01463a027.
- ^ Huang, Jen-How; Matzner, Egbert (2004). "Biogeochemistry of organotin compounds and tin in a forested catchment in Germany". Science of the Total Environment. 332 (1–3): 231–241. Bibcode:2004ScTEn.332..231H. doi:10.1016/j.scitotenv.2004.04.015. PMID 15336905.
- ^ Zhang, Xu; Yang, Huanhuan; Cui, Yan; Ren, Zhen; Sun, Ruirui (2021). "Comparison of two extraction methods for the determination of organolead compounds using sodium tetrapropylborate as derivatization reagent". Resources, Environment and Sustainability. 6. Bibcode:2021REnvS...600035Z. doi:10.1016/j.resenv.2021.100035.